Divergence of cytokinesis and dimorphism control by myosin II regulatory light chain in fission yeasts.

Non-muscle myosin II activation by regulatory light chain (Rlc1) phosphorylation at Ser35 is crucial for cytokinesis during respiration in the fission yeast We show that in the early divergent and dimorphic fission yeast non-phosphorylated Rlc1 regulates the activity of Myo2 and Myp2 heavy chains during cytokinesis. Intriguingly, Rlc1-Myo2 nodes delay yeast to hyphae onset but are essential for mycelial development. Structure-function analysis revealed that phosphorylation-induced folding of Rlc1 α1 helix into an open conformation allows precise regulation of Myo2 during cytokinesis.

Myosin II regulatory light chain phosphorylation and formin availability modulate cytokinesis upon changes in carbohydrate metabolism.

Cytokinesis, the separation of daughter cells at the end of mitosis, relies in animal cells on a contractile actomyosin ring (CAR) composed of actin and class II myosins, whose activity is strongly influenced by regulatory light chain (RLC) phosphorylation. However, in simple eukaryotes such as the fission yeast , RLC phosphorylation appears dispensable for regulating CAR dynamics. We found that redundant phosphorylation at Ser35 of the RLC homolog Rlc1 by the p21-activated kinases Pak1 and Pak2, modulates myosin II Myo2 activity and becomes essential for cytokinesis and cell growth during respiration.

cAMP-Protein kinase A and stress-activated MAP kinase signaling mediate transcriptional control of autophagy in fission yeast during glucose limitation or starvation.

Macroautophagy/autophagy is an essential adaptive physiological response in eukaryotes induced during nutrient starvation, including glucose, the primary immediate carbon and energy source for most cells. Although the molecular mechanisms that induce autophagy during glucose starvation have been extensively explored in the budding yeast , little is known about how this coping response is regulated in the evolutionary distant fission yeast . Here, we show that autophagy in response to glucose limitation relies on mitochondrial respiration and the electron transport chain (ETC), but, in contrast to , the AMP-activated protein kinase (AMPK) and DNA damage response pathway components do not modulate fission yeast autophagic flux under these conditions.

The Fission Yeast Cell Integrity Pathway: A Functional Hub for Cell Survival upon Stress and Beyond.

The survival of eukaryotic organisms during environmental changes is largely dependent on the adaptive responses elicited by signal transduction cascades, including those regulated by the Mitogen-Activated Protein Kinase (MAPK) pathways. The Cell Integrity Pathway (CIP), one of the three MAPK pathways found in the simple eukaryote fission of yeast , shows strong homology with mammalian Extracellular signal-Regulated Kinases (ERKs). Remarkably, studies over the last few decades have gradually positioned the CIP as a multi-faceted pathway that impacts multiple functional aspects of the fission yeast life cycle during unperturbed growth and in response to stress.

Health status of free-ranging pure and cross-mixed miniature swine population from Northeast Spain.

Background: Miniature pigs have gained popularity as companion animals in the recent years in Spain. Due to the fact that their abandonment and crossing breeds with wild boars can cause severe problems, investigation about the health status is needed.

Objectives: The aim of this study was to determine their health status according to the clinical findings during physical examination and the results of antibody serology tests against selected infectious diseases.

The Multiple Functions of Rho GTPases in Fission Yeasts.

The Rho family of GTPases represents highly conserved molecular switches involved in a plethora of physiological processes. Fission yeast has become a fundamental model organism to study the functions of Rho GTPases over the past few decades. In recent years, another fission yeast species, , has come into focus offering insight into evolutionary changes within the genus.

Specific Functional Features of the Cell Integrity MAP Kinase Pathway in the Dimorphic Fission Yeast .

Mitogen activated protein kinase (MAPK) signaling pathways execute essential functions in eukaryotic organisms by transducing extracellular stimuli into adaptive cellular responses. In the fission yeast model the cell integrity pathway (CIP) and its core effector, MAPK Pmk1, play a key role during regulation of cell integrity, cytokinesis, and ionic homeostasis. , another fission yeast species, shows remarkable differences with respect to , including a robust yeast to hyphae dimorphism in response to environmental changes.

Paradoxical Vestibular Syndrome Caused by a Presumptive Cerebellar Infarction in a Rabbit.

A 6-year-old, female spayed rabbit (Oryctolagus cuniculus) presented with right paradoxical vestibular signs. Magnetic resonance imaging was performed and findings were consistent with an ischemic infarct of the cerebellum. The patient improved gradually and was free of clinical signs at the time this article was written.

Stress-activated MAPK signaling controls fission yeast actomyosin ring integrity by modulating formin For3 levels.

Cytokinesis, which enables the physical separation of daughter cells once mitosis has been completed, is executed in fungal and animal cells by a contractile actin- and myosin-based ring (CAR). In the fission yeast the formin For3 nucleates actin cables and also co-operates for CAR assembly during cytokinesis. Mitogen-activated protein kinases (MAPKs) regulate essential adaptive responses in eukaryotic organisms to environmental changes.

RNA-Binding Protein Rnc1 Regulates Cell Length at Division and Acute Stress Response in Fission Yeast through Negative Feedback Modulation of the Stress-Activated Mitogen-Activated Protein Kinase Pathway.

RNA-binding proteins (RBPs) play a major role during control of mRNA localization, stability, and translation and are central to most cellular processes. In the fission yeast , the multiple K homology (KH) domain RBP Rnc1 downregulates the activity of the cell integrity pathway (CIP) via stabilization of mRNA, which encodes the Pmp1 phosphatase that inactivates Pmk1, the mitogen-activated protein kinase (MAPK) component of this signaling cascade. However, Rnc1 likely regulates the half-life/stability of additional mRNAs.

Correction: Quorum sensing and stress-activated MAPK signaling repress yeast to hypha transition in the fission yeast Schizosaccharomyces japonicus.

[This corrects the article DOI: 10.1371/journal.pgen.

Quorum sensing and stress-activated MAPK signaling repress yeast to hypha transition in the fission yeast Schizosaccharomyces japonicus.

Quorum sensing (QS), a mechanism of microbial communication dependent on cell density, governs developmental decisions in many bacteria and in some pathogenic and non-pathogenic fungi including yeasts. In these simple eukaryotes this response is mediated by the release into the growth medium of quorum-sensing molecules (QSMs) whose concentration increases proportionally to the population density. To date the occurrence of QS is restricted to a few yeast species.

Differential functional regulation of protein kinase C (PKC) orthologs in fission yeast.

The two PKC orthologs Pck1 and Pck2 in the fission yeast operate in a redundant fashion to control essential functions, including morphogenesis and cell wall biosynthesis, as well as the activity of the cell integrity pathway and its core element, the MAPK Pmk1. We show here that, despite the strong structural similarity and functional redundancy of these two enzymes, the mechanisms regulating their maturation, activation, and stabilization have a remarkably distinct biological impact on both kinases. We found that, in contrast to Pck2, putative phosphorylation of Pck1 within the conserved activation loop, turn, and hydrophobic motifs is essential for Pck1 stability and biological functions.

Multiple crosstalk between TOR and the cell integrity MAPK signaling pathway in fission yeast.

In eukaryotic cells, the highly conserved Target of Rapamycin (TOR) and the Mitogen Activated Protein Kinase (MAPK) signaling pathways elicit adaptive responses to extra- and intracellular conditions by regulating essential cellular functions. However, the nature of the functional relationships between both pathways is not fully understood. In the fission yeast Schizosaccharomyces pombe the cell integrity MAPK pathway (CIP) regulates morphogenesis, cell wall structure and ionic homeostasis.

Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands.

The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago.

Multiple layers of regulation influence cell integrity control by the PKC ortholog Pck2 in fission yeast.

The fission yeast protein kinase C (PKC) ortholog Pck2 controls cell wall synthesis and is a major upstream activator of the cell integrity pathway (CIP) and its core component, the MAP kinase Pmk1 (also known as Spm1), in response to environmental stimuli. We show that in vivo phosphorylation of Pck2 at the conserved T842 activation loop during growth and in response to different stresses is mediated by the phosphoinositide-dependent kinase (PDK) ortholog Ksg1 and an autophosphorylation mechanism. However, T842 phosphorylation is not essential for Pmk1 activation, and putative phosphorylation at T846 might play an additional role in Pck2 catalytic activation and downstream signaling.

New evidence of early Neanderthal disappearance in the Iberian Peninsula.

The timing of the end of the Middle Palaeolithic and the disappearance of Neanderthals continue to be strongly debated. Current chronometric evidence from different European sites pushes the end of the Middle Palaeolithic throughout the continent back to around 42 thousand years ago (ka). This has called into question some of the dates from the Iberian Peninsula, previously considered as one of the last refuge zones of the Neanderthals.

Rho2 palmitoylation is required for plasma membrane localization and proper signaling to the fission yeast cell integrity mitogen- activated protein kinase pathway.

The fission yeast small GTPase Rho2 regulates morphogenesis and is an upstream activator of the cell integrity pathway, whose key element, mitogen-activated protein kinase (MAPK) Pmk1, becomes activated by multiple environmental stimuli and controls several cellular functions. Here we demonstrate that farnesylated Rho2 becomes palmitoylated in vivo at cysteine-196 within its carboxyl end and that this modification allows its specific targeting to the plasma membrane. Unlike that of other palmitoylated and prenylated GTPases, the Rho2 control of morphogenesis and Pmk1 activity is strictly dependent upon plasma membrane localization and is not found in other cellular membranes.

Role of the fission yeast cell integrity MAPK pathway in response to glucose limitation.

Background: Glucose is a signaling molecule which regulates multiple events in eukaryotic organisms and the most preferred carbon source in the fission yeast Schizosaccharomyces pombe. The ability of this yeast to grow in the absence of glucose becomes strongly limited due to lack of enzymes of the glyoxylate cycle that support diauxic growth. The stress-activated protein kinase (SAPK) pathway and its effectors, Sty1 MAPK and transcription factor Atf1, play a critical role in the adaptation of fission yeast to grow on alternative non-fermentable carbon sources by inducing the expression of fbp1+ gene, coding for the gluconeogenic enzyme fructose-1,6-bisphosphatase.

Biological significance of nuclear localization of mitogen-activated protein kinase Pmk1 in fission yeast.

Mitogen-activated protein kinase (MAPK) signaling pathways play a fundamental role in the response of eukaryotic cells to environmental changes. Also, much evidence shows that the stimulus-dependent nuclear targeting of this class of regulatory kinases is crucial for adequate regulation of distinct cellular events. In the fission yeast Schizosaccharomyces pombe, the cell integrity MAPK pathway, whose central element is the MAPK Pmk1, regulates multiple processes such as cell wall integrity, vacuole fusion, cytokinesis, and ionic homeostasis.

Stress-activated protein kinase-mediated down-regulation of the cell integrity pathway mitogen-activated protein kinase Pmk1p by protein phosphatases.

Fission yeast mitogen-activated protein kinase (MAPK) Pmk1p is involved in morphogenesis, cytokinesis, and ion homeostasis as part of the cell integrity pathway, and it becomes activated under multiple stresses, including hyper- or hypotonic conditions, glucose deprivation, cell wall-damaging compounds, and oxidative stress. The only protein phosphatase known to dephosphorylate and inactivate Pmk1p is Pmp1p. We show here that the stress-activated protein kinase (SAPK) pathway and its main effector, Sty1p MAPK, are essential for proper deactivation of Pmk1p under hypertonic stress in a process regulated by Atf1p transcription factor.

Solubilization and characterization of a cell wall-bound trehalase from ascospores of the fission yeast Schizosaccharomyces pombe.

The genome of the fission yeast Schizosaccharomyces pombe lacks sequence homologs to ath1 genes coding for acid trehalases in other yeasts or filamentous fungi. However, acid trehalase activity is present at the spore stage in the life cycle of the fission yeast. The enzyme responsible for this activity behaves as a surface enzyme covalently linked to the spore cell walls in both wild-type and ntp1 mutant strains devoid of neutral trehalase.

Paleobiology and comparative morphology of a late Neandertal sample from El Sidron, Asturias, Spain.

Fossil evidence from the Iberian Peninsula is essential for understanding Neandertal evolution and history. Since 2000, a new sample approximately 43,000 years old has been systematically recovered at the El Sidrón cave site (Asturias, Spain). Human remains almost exclusively compose the bone assemblage.